CASSJAVA-68 Improve DefaultCodecRegisry.CacheKey#hashCode() to eliminate Object[] allocation (found via profiler)

tatu-at-datastax · absurdfarce · commit 53bb5c8b6580 · 2025-04-29T16:06:54.000-05:00
patch by Tatu Saloranta; reviewed by Dmitry Konstantinov and Bret McGuire for CASSJAVA-68
diff --git a/core/src/main/java/com/datastax/oss/driver/internal/core/type/codec/registry/DefaultCodecRegistry.java b/core/src/main/java/com/datastax/oss/driver/internal/core/type/codec/registry/DefaultCodecRegistry.java
@@ -159,7 +159,10 @@ public boolean equals(Object other) {
 
     @Override
     public int hashCode() {
-      return Objects.hash(cqlType, javaType, isJavaCovariant);
+      // NOTE: inlined Objects.hash for performance reasons (avoid Object[] allocation
+      // seen in profiler allocation traces)
+      return ((31 + Objects.hashCode(cqlType)) * 31 + Objects.hashCode(javaType)) * 31
+              + Boolean.hashCode(isJavaCovariant);
     }
   }
 }

Original file line number	Diff line number	Diff line change
`@@ -159,7 +159,10 @@ public boolean equals(Object other) {`
`159`	`159`
`160`	`160`	`@Override`
`161`	`161`	`public int hashCode() {`
`162`		`- return Objects.hash(cqlType, javaType, isJavaCovariant);`
	`162`	`+ // NOTE: inlined Objects.hash for performance reasons (avoid Object[] allocation`
	`163`	`+ // seen in profiler allocation traces)`
	`164`	`+ return ((31 + Objects.hashCode(cqlType)) * 31 + Objects.hashCode(javaType)) * 31`
	`165`	`+ + Boolean.hashCode(isJavaCovariant);`
`163`	`166`	`}`
`164`	`167`	`}`
`165`	`168`	`}`